Automatic pressure-controller.



C. S. JBNNINGS.

AUTOMATIC PRESSURE CONTROLLER.

APPLICATION FILED SEPT. 19, 190e.

Patented Mar. 23, i915.

y nUNIT-ED STATES PATENT FFXCEe CHESTER S. J'ENNINGS, 0F BROKLINE,MASSACHUSETTS, ASSIGNOR T0 THE LAMSON' comnNY, or NEWARK, NEW JERSEY,

A CORPORATION 0F NEW JERSEY.

AUTOMATIC PRESSURE-CONTROLLER.

Specification of Letters Patent.

Patented Mar. 23, 1915.

T0 all Iwhom z'tmag/ concern.'

lle it known that I, CHESTER S. JENNINGS, of Brookline, in the county ofNorfolk and State of Massachusetts, have invented certain new and usefulImprovements in Automatic Pressure-Controllers, of which the followingis a specification.

My invention relates to power controlling apparatus, such for example,as may be used in a pneumatic despatch tube system to maintain apredetermined vacuum or pressure in the tubes. ln these despatch tubesystems a blower or pump is employed to produce a Ipressure or vacuum inthe transmission tubes, and the blower is driven by a motor whose speedis regulated so as to control the action of the blower or pump andmaintain uniform or substantially unii'orm pressure in the system.

M v invention relates particularly to means for controlling the motoraccording to the pressure in the system. and its object is to producesimple and efiicient means to automatically control the action of themotor according to the pressure in the system with which the pump isconnected.

l To these ends my invention consists of the combination with the airpump and an electric motor for driving the same, of a variableresistance in circuit with said motor and means for regulating thisresistance in circuit with said motor and means for regulating thisresistance comprising a pair of `auxiliary motors, one for increasingthe resistance in the motor circuit and the other for diminishing theresistance in the motor circuit.'and means controlled by the pressure inthe. transmission tubes or other chamber with which the pump isconnected for selecting and operating one or the other oiisaid motorsaccording to the variation of pressure in the tubes, so as to increasethe resistance when the pressure varies in one direction. and todiminish the resistance when the pressure varies in the oppositedirection.

Other features of. my invention are hereinafter pointed out.

1n the accompanying drawings in which' is illustrated a form ofconstruction embodying my invention, Figure 1 is a diagram -of thedevice in connection with the supply pipe of a pneumatic despatch tubesystem; Fig. 2 is a plan view of the automatic controlling rheostat;Fig. 8 shows a section of the supply pipe of a pneumatic system showingdiaphragm and switch connected therewith.

Like letters of reference refer to like parts throughout the severalViews.

1 represents a blower adapted to exhaust air from or supply air to thesupply pipe 2, which is here intended to represent part of a pneumaticdespatch tube system.

3 is the electric motor which operates the pump l through the belt L1; 5is the usual switch or rheostat that is used only in starting andstopping the motor 3. The circuit oi the field of the motor 3 is asfollows: from the line wire 6 by wires T and 8 to one end of the Iieldwinding and from the other end of the field winding by wires 9 and lO toa series of resistances 11. Thence via a ratchet wheel 12 and wire 13 tothe starting rheostat 5. and from the rheostat 5 by wire 14 to line wire15. rThe circuit of the armature of the motor 3 is from the junction ofwires 7 and S by the wire 16 to brush 17; through the armature and brush18 to wire 19 and thence by a wire 2O to starting switch 5 where itjoins the wire 14. The resistances 11 are connected with contacts Q1which are in the path ot an arm Q2 carried by the ratchet 12. rlhisratchet 12 is loose on a stud Q2 that also carries two arms 23 and Q4.The arms Q3 and 24 carry opposed pawls 25 and 25 to engage the ratchet12 and as will be clear, when one of said arms is vibrated, the ratchetwheel 12 will be rotated step by step in one direction, and when theother of said arms is vibrated, the ratchet wheel will be rotated stepby step in the opposite direction. The arm 23l is connected by a link26a with a rod 2G, and said rod extends through a coil 27, the rod Q6and coil Q7 constituting a solenoid. At its upper end. the rod Q6extends into a cylinder 28 and has fastened to it a piston 29. Thepiston 29 and cylinder 28 constitute a dash pot to yieldingly resist orretard the movement of said rod. The piston is made with ports 30through it for the passage of the contents within the cylinder from oneside of the piston to the other as said piston moves with the rod. Alsoin order to provide Jfor regulating the resistance offered by thecontents. the cylinder 28 is made with a. bypass 31 which is controlledby the valve screw 32. ln this way, the action of the dash pot may beregulated to control the speed of this auxiliary motor made up Vot thecoil 27 and rod 26. rlhe coil 27 and cylinder 28 are fixed to the baseplate 33, and .this base plate 33 also carries a pair of contacts 34coperating with a bridge piece 35 carried by but insulated from a frame36 on rod 26. IThis bridge piece is so adjusted that when the rod 26 isat its lowest point, the contacts 34 are connected, but when currentiiows through coil 27, the rod 26 is lifted and the bridge piece 35 iscarried away from contacts 34. The contacts 34 are in circuit with coil27 and therefore the current is cut oli from said coil as soon as therod 26 is lifted and the rod 26-iialls back to its lowermost positionagain, upon reaching which the bridge piece re'stablishes the connectionbetween contacts 34 and the rod is again lifted.

The erin 24 is connected by a link 37 with a rod 33 extending1 through acoil 39 iXed to the plate `33 and projecting at its upper end into thecylinder 40. The rod 33 carries at its upper end a piston 4f. and saidpiston and cylinder 4U like the cylinder 28 and piston 23,*constitute adash pot. Alongside ci coil 39 is a pair ci contacts 42 .fixed to plate33 so as to cooperate with a bridge piece 43 carried by a trame 44emerod 38'. The pipe 2 is cut away as at 45, and in this opening is iixed adiaphragm 46 pivoted at its middle 47 to a lever 43 pivoted at 49 to theframe 56 surrounding the opening 45. The lever 48 at one end carries twobridge pieces 5l and 52 and at its other end said lever is acted upon bythe spring 53 whose pressure is adjusted by means or a screw 54 -so thatwhen the predetermined normal vacuuin or pressure exists in the pipe 2,the lever 48 is balanced with the bridge pieces 5l and 52 out ofengagement with the contacts 56, 57 58 and 59. The two contacts 56 and53 are connected by the wires 60 and 7 with line wire 6, while contact59 is connected by wire 61 with one ot the contacts 34. 'llhe othercontact 34 is connected by wire 62-with one end 0i the Icoil 27. Theother end of the coil 27 is connected by wires sa, et ana it with im@wir@ i5. 'rile coatact 57 is connected by the wire 65 with one of thecontacts 42 andthe other contact 42 is connected by the wire 66 with oneend of the coil 39 the other end of said coil being `connected with thewire 64, which is in turn connected through the wire 14 with the linewire l5. lt will thus be seen that when the pressure in the pipe 2varies in one direction, ythe contacts 56 and 57 will be connected and39 and rod 38 will be reciprocated as above described so as to rotatethe ratchet wheel l2 in a direction to increase the resistancein thecircuit of the motor '3. llt will also be a circuit will be completedthrough the coil' seen when the pressure in the pipe 2 varies in theopposite direction, the bridge piece 52 will connect contacts 58 and 59and the circuit will be completed throughA the coil 27 and rod 26 willbe reciprocated as above described to rotate the ratchet wheel 12 in theopposite direction so as to reduce the re- Y sistance in the circuit ofthe motor 3.

There is thus provided a pair of motors, each of which actuates theratchet l2 intermittently, that is, step by step, one serving to rotatesaid ratchet in one direction and the other serving to rotate saidratchet in the opposite direction. rlhe advantage ci this is that thereis an interval of time between the step movements oi the ratchet l2 toallow the change of resistance in the circuit oie motor 3 to act throughmotor 3 and pump l on the pressure in the pipe 2 betore the resistanceis again changed.

ln the constructions heretofore proposed, a rotating motor has beenemployed which was started, stopped and reversed to control theresistance in the circuit of the pun'ip driving,7 motor, but theobjection to this construction `has been either that when the motor wasstopped its momentum would carry it beyond the necessary point after itscurrent was automatically cut oii" by the pressure in the pipe, or thelike, or that the delay in overcoming the inertia oi the motor whenstarted by the automatic pressurecontrolled means delayed the changingoi the resistance in the motor circuit. @n the other hand, thisapparatus is quickly rei `sponsive to any kchange or pressure in thepipe 2 beyond a predetermined point and the resistance in the circuit ofthe motor is accurately varied according to changes or? pressure in pipe2.

Having thus described the nature or nay invention and set orth aconstruction ernbodying the same, what claim as new and desire to secureby Letters lpatent ci the United States is:

l. ln an automatic pressure controller, the combination oi anair-transmission tube, a pump communicating with said tube, an electricmotor for driving said pump, a variable resistance in circuit with saidmotor, and .means for regulating' .the resistance o said motor circuitcomprising` two auxiliary motors with one acting to increase theresistance in said circuit and the other for diminishing the resistancein said ciry cuit, and means controlled from substantially but a singlepoint by the pressure in said air-transmission tube for selecting andsingly operating one or the other of said auxiliary motors according tothe variation oi pressure in said tube, so that one of said auxiliarymotors when selected will increase the resistance in said circuit whenthe pressure varies in the tube in one direction, and the other oi saidauxiliary motors when lll@ selected will diminish the resistance in saidcircuitwhen the pressure in the tube varies in the other direction.

2. Inan automatic pressure controller, the combination of anair-transmission tube, a pump communicating with said tube, an electricmotor for driving said pump, a variable resistance in circuit with saidmotor, and means for regulating the resistanceV of said motor circuitcomprising two auxiliary motors with one substantially invariablyacting, Whenever operative, to increase the resistance in said circuitand the other for similarly diminishing theresistance in said circuit,and means controlled by pressures in said air-transmission tube of butone sign, atmospheric pressure being regarded as zero for the purpose ofdetermining said sign, said means adapted to select and operate one orthe .other` of said auxiliary motors according to the change of pressurein said tube either Way from a determined normal pressure to bemaintained therein, so that one of said auxiliary motors when selectedwill increase the resistance in said circuit when the pressure varies 1nthe tube in one direction, and the other of said auxiliary motors whenselected will d1- minish the resistance in said circuit when thepressure in the tube varies in the other direction.

3. In an automatic pressure controller, the combination of anair-transmission tube, a pump communicating with said tube, an electricmotor for driving said pump, a va riable resistance in circuit with saidmotor, and means for regulating the resistance of said motor circuitcomprising two auxiliary motors with one acting to increase theresistance in said circuit and the other for diminishing the resistancein Ysaid circuit, and means controlled by the pressure in saidair-transmission tube for selecting and operating one or the other ofsaid auxiliary motors while leaving the other idle, according to thevariation of pressure in said tube, so that one of said auxiliary motorswhen selected will increase the resistance in said circuit when thepressure varies in the tube in one direction, andthe other of saidauxiliary motors when selected will diminish the resistance in saidcircuit when the pressure in the tube varies in the other direction,said motors having provisions for gradually varying said resistancesubstantially regardless of violent and sudden variations in pressure insaid tube.

4. In an automatic pressure controller, the combination of anair-transmission tube, a pump communicating with said tube, an electricmotor for driving said pump, a variable resistance in circuit with' saidmotor. and means for regulating the resistance of said motor circuitcomprising two auxiliary motors, independently driven with respect tosaid pump, with one acting to increase the resistance insaid circuit andthe other for diminishing the resistance in said circuit, and meanscontrolled by the pressure in said air-transmission tube for selectingand operating one or the other of said auxiliary motors according to thevariation of pressure in said tube, so that one of said auxiliary motorswhen selected will increase the resistance in said circuit when thepressure varies in the tube in one direction, and the other of saidauxiliary motors when selected will diminish the resistance in saidcircuit when the pressure in the tube varies in the other direction.

5. In an automatic pressure controller, the combination of anair-transmission tube, a pump communicating with said tube, an electricmotor for driving said pump, a variable resistance in circuit with saidmotor, and means for regulating the resistance of said motor circuitcomprising two auxiliary motors with one acting to increase theresistance in said circuit and the other for diminishing the resistancein said circuit, and a device controlled by the pressure in saidair-transmission tube for selecting and operating singly one or theother of said auxiliary motors according to the variation of pressure insaid tube, so that one of said auxiliary motors when selected Willincrease the resistance in said circuit when the pres- Y sure varies inthe tube in one direction, and the other of said auxiliary motors whenselected will diminish the resistance in said circuit when thevpressurein the tube varies in the other direction.

In testimony whereof, I have signed my name to this specification in thepresence of two subscribin witnesses, this fifteenth day of September D.1906.

CHESTER S. J ENNINGS.

Witnesses:

HOWARD R. DUNBAR, H. D. WATERHoUsE.

